Module 5 Laboratory Flashcards
basic mechanism for contraction (3)
(1) electrical excitation of muscle cell
(2) excitation-contraction coupling
(3) sliding of muscle filaments or contraction
electrical potential difference across the muscle cell membrane equal to approximalely
-80mV
inside of the mebrane is negatively/postively charge
negatively
____ is stimulated either by direct electric shock or by the motor nerve that innervates the muscle
muscle cell
what diffuses into the cell that depolarizes the membrane and its polarity momentarily reverses
Na+
diffuses out of the cell membrane which repolarizes the membrane and establishes the more negative resting membrane potential
K+
rapid depolarization and repolarization of the membrane at the stimulated point
action potential
as action potentials are conducted along the muscle cell membrane, they stimulate a rise in the cytoplasmic concentration of what
Ca2+
Ca2+ comes from a system of intracellular tubules called the
sarcoplasmic reticulum
in the resting muscle, the absence of this calcium allows two (2) proteins to inhibit contraction
troponin
tropomyosin
as a result of electrical stimulation, Ca2+ is released into the cell and becomes attached to what protein
troponin
complex that have their inhibitory effect removed
troponin-tropomysin complex
the influx of what is said to couple electrical excitation to muscle contraction
calcium ions
oriented parallel to the long axis of the fiber within the muscle cell
fibrils
repeating subunits in each fibril
sarcomere
functional unit of contraction
sarcomere
thick filament
myosin
thin filament
actin
as the sarcomeres becomes shorter, the fibrils and thus the entire muscle cell shorten, resulting in ____
muscle contraction
skeletal muscles are stimulated to contract by which nerves
somatic motor nerves
neurotransmitter that is released when action potentials in the mother nerves elicit this response
acetlycholine
causes ca2+ to be released from the sarcoplasmic reticulum
electrical stimulation
produces an injury current that stimulates action potentials and subsequent muscle contractions when for example, a somatic nerve is pinched
damagee
secondary to nerve damage or to dysfunctions at the neuromuscular junctions
muscle degeneration